Like most parts of the human body, our eyes gradually deteriorate over time.
A new she studies they now show how stress can speed up this aging process, a finding that could help us treat eye problems that develop as we age, including the group of vision-loss-causing diseases known as glaucoma.
While the research is based on tests in mice, the team believes the same principles will likely apply to human eyes.
A common consequence of psychological stress in even the healthiest people is an increase in intraocular pressure (IOP, also known as ocular hypertension), or fluid pressure in the eye. Known to be linked to the development of glaucoma, it appears that the physiological stress of increased IOP may also be linked to markers of biological aging, which can appear as changes in the molecular tags on DNA and proteins that control which genes are active or not.
“The epigenetic changes we observed suggest that changes in chromatin are acquired cumulatively as a result of multiple instances of stress,” says ophthalmologist Dorota Skowronska-Krawczyk of the University of California, Irvine (UCI) School of Medicine.
“This gives us a window of opportunity to prevent vision loss if and when the disease is recognized early.”
The team looked at the optic nerve head of the mouse’s eyes – the point where the retinal cells at the back of the eye converge to form the nerve that goes to the brain – where IOP was artificially increased. In younger mice, there was little difference from control animals, but in older mice, those with mildly elevated eye pressure showed loss of axons or nerve fibers, which also occurs in cases of glaucoma.
In other words, older mice appeared more susceptible to changes in eye pressure, leading to inflammatory damage and a gradual loss of cellular function that would normally take years to develop naturally.
A remarkable discovery
In humans, IOP is not fixed but fluctuates throughout the day. More extreme and prolonged fluctuations have previously been associated with glaucoma progression and the researchers behind the new one she studies I believe that the cumulative effect of these fluctuations – and the pressure they put on the eye – is responsible for the aging of the tissue.
“Our work shows that even moderate increases in hydrostatic IOP result in retinal ganglion cell loss and corresponding visual defects when performed in aged animals,” says Skowronska-Krawczyk.
“We continue to work on understanding the mechanism of accumulated changes in aging to find potential targets for therapies. We are also testing different approaches to prevent the accelerated aging process that results from stress.”
Now that they’ve detected these pressure-induced changes, the researchers believe they can use it as a way to assess the epigenetic age of eye tissue — the amount of wear, essentially — and thus make treatments more targeted and better personalized for each individual. patient.
Aside from psychological stress, there are a number of other factors that can cause increased pressure within the eye, from genetics to eye trauma to medications. As IOP increases, having a means to study its impact could save millions of people’s eyesight.
As the world’s population ages, the number of glaucoma cases is projected to rise and could reach 110 million by 2040. Left untreated, these conditions can lead to blindness.
While there’s no way to completely reverse the damage from glaucoma, it can be managed — and being able to detect it (and the causes leading to it sooner) would make a significant difference in vision loss.
“Our work highlights the importance of early diagnosis and prevention, as well as age-specific management of age-related diseases, including glaucoma,” says Skowronska-Krawczyk.